After three months of talking between the Greek government and inspectors from the IMF [International Monetary Fund], the EU and the ECB [European Central Bank], they have narrowed the differences over the savings Greece must make in order to qualify for the next tranche of money.

The mood music from the politicians has been positive. The Greeks, we are told in Brussels, are this time serious about reform.

The German chancellor signals her support for Greece by flying to Athens.

German Finance Minister Wolfgang Schaeuble is more explicit. He does not think there will be a Greek default: "We do not see that there is any sense to speculate on Greece leaving the euro, that would be very damaging for Greece and the euro."

Most of the summer talk about Greece leaving the euro has evaporated.

But here is the problem. The Greek government and the troika are still arguing over the figures, although they are close.

The main problem is that once again, the depth of the Greek recession has been underestimated. Tax revenues are down and the shrinking economy undermines projections.

Even so, heads of government this week at a summit in Brussels may well end up discussing a new deal for Greece if the talks in Athens succeed.

Almost certainly Greece will be given two more years to meet its commitments. The IMF backs this and so do most of the eurozone finance ministers.

More time, as Mr Schaeuble pointed out, means more money. Perhaps 20bn euros (£16bn). Perhaps more. That will have to be found. Even so, that is the easier part.

Hard choices

The strategy was for Greece to bring its debt-to-GDP ratio down to 120% by 2020. That clearly will not happen.

The IMF predicts a ratio next year of 182%. By 2020, the IMF believes they might get the figure down to 140%. The European Commission is a touch more optimistic.

What all this means is that the current plan is not sustainable. It is not working.

The Greek economy, with a few exceptions, is in free fall. Sooner rather than later, a cold choice will have to be made.

Will there be a restructuring of debt (with this time national governments and the ECB taking losses), or will there be a third bailout, or will the politicians accept the medicine is not working?

The pervading sense of unreality was broken this week by Swedish Finance Minister Anders Borg who was quoted as saying: "It is most probable they [the Greeks] will leave."

That may or may not be true, but a Greek exit cannot be said to be off the table until the key question has been answered: How will the Greek debt mountain be reduced?